How to Build a Sap Wood Water Filter

As per the World Health Organization, over 1.5 million people are victims of dehydration and diseases caused by polluted water. Stale water is a breeding ground for protozoa, bacteria, viruses, and parasites, which can cause diseases like dysentery, gastroenteritis, hepatitis, Giardia, and norovirus. But thankfully, as societies developed, we discovered ways to filter and clean our drinking water through boiling, chlorinating, filtration, pasteurization, and even iodine pills. Yet, when you’re in the wilderness in a survival scenario, a lot of the aforementioned methods are not going to be available and as such, learning alternative methods of purifying water becomes a top priority. Thankfully, the brilliant minds at MIT have your back with a unique type of water filter that can raise your chance of survival even without potable water. This filter is made from pine trees.

How Does a Conifer Filter Work?

Trees and plants need clean water to survive. Just like other living organisms, the chance of getting sick increases in the presence of bacteria, parasites, and other contaminants. But, nature doesn’t have all the fancy technology that we humans have available, so what can plants do to clean their own drinking supply? Surely, trees can’t only sustain themselves on the rain, can they? The answer is no, they can’t, but thanks to an evolutionary advantage, they are filled to the brim with xylem vessels. These vessels are tubes that provide nutrients and water from the ground, through the roots, all the way to the stems of each branch. Interestingly enough, the vessels are composed mostly of dead cells that create a fortified, porous wall at their sides. These are also arranged in a pattern that is large enough for water to flow through, but minuscule enough to prevent bacteria and microbes from doing the same.

Believer or not, in conifers, the xylem vessel cells are actually smaller than in trees who yield flowers or plants. While this means they can’t transport sap as efficiently, it makes them great filters in the wild. A higher number of xylem vessels means that a filter using conifers requires a smaller quantity of branches to filter more water. During the test run at MIT, they utilized a mere three cubic centimeters of pine stem each day, and it provided enough water for a single person to still maintain healthy hydration levels.

Making a Sapwood Filter

The filtering properties of xylem filters are so effective at eliminating certain contaminants that when utilizing water contaminated by E.coli, the researchers found a 99.9% reduction in the number of pollutants after the filtration process was completed. However, while conifer xylem vessels are small enough to filter out bacteria, they are unable to filter out viruses. It’s quite possible that other trees with smaller vessels can perform better at that type of job. Research is still ongoing. But, now that we’ve covered all the benefits of a xylem filter, just how do we make one out in the wild?

Well, a little preparation is required, what you’ll need to gather and have in handy are:

  • Plastic tube, 1-2″ diameter, 12-24″ long
  • A hose clamp to fit around the tube
  • Freshly cut conifer branch that will fit tightly into the tube
  • Empty catch container

To begin with, cut a one-inch section off of the branch. Peel off all the bark and insert the sapwood into the plastic tubing. Tighten the hose clamp around the bottom of the tube, holding the wood in place. Fill the tube with water, and tighten the hose clamp until no water seeps out between the wood and the tube. Slide the tube into a container, keeping the tube raise high enough where it won’t come in contact with the clean water as it fills the container. Allow gravity to filter the water through conifer into the container. The water filtered at the bottom should be clean of most bacteria and rendered safer (not completely safe) to drink. Refill the tube as needed.

Sapwood Filter Caveats

It’s important to remember that while it will remove bacteria, a conifer filter is unlikely to eliminate any viruses in the water. A secondary, but no less important, aspect is that the wood must be freshly cut in order to work as a filter. According to the study, the xylem vessels clog up as the wood dries out, and will no longer filter water. As such, it is only effective if you have an ample supply of wood that can be cut. While this means you can’t purchase a supply of conifer filters in advance, it also means that you’ll need some rudimentary knowledge of botany in order to identify which trees are better filters than others.

(Bacteria being caught in narrow passages called xylem)

Xylem vessel filtration systems are a big advancement in the world of survival. While the systems themselves will not be able to eliminate viruses that can cause deadly diseases, it could potentially mean the difference between survival and death in a real-world scenario. They are cheap and fairly accessible to many people, and these types of filters come with the added perk of biodegradability by virtue of using wood. Xylem vessel filters are not perfect, but in a survival scenario, you need every single advantage you can.

Disclaimer: The content in this article is the opinion of the writer and does not necessarily reflect the policies or opinions of US Patriot Tactical.

Emmanuel "Dash the Bomber" Barbosa

Emmanuel Barbosa, AKA Dash The Bomber, is currently serving in the 7th fleet, and has over 8 years of experience in the military. A writer with a penchant for the humorous and informative, he loves to share his stories with those who would be willing to listen. Having served in deployments that have taken him around the world, Dash has seen and heard about many things that would be hard to believe. A loving father and a faithful husband, he is dedicated to protecting his family and country. For fun he enjoys cosplaying, videogames, and writing for online magazines.

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